In the context of gas turbine maintenance, it is sometimes necessary to replace components such as burners or transition pieces. The components are typically attached by means of a component flange to a matching component mating flange, for example on the casing of the gas turbine. Thus, for example a burner is connected by means of a burner flange to a matching burner mating flange, and attached to the casing of the gas turbine. In order to replace the component, the connections of the flange or of the mating flange must be released and the component as a whole must be removed. During this work, the available maintenance spaces can be very small since a great number of lines, pipes and cables in the region of the casing can greatly restrict the space available for movement. In order to provide more space, it would be necessary to remove these lines, pipes or cables, which would however greatly increase the work involved in maintenance. If, as in the operational arrangement of the gas turbine, the components are arranged in the lower region of the gas turbine casing, the use of a hoist for carrying the load is very difficult since the typical load-bearing ropes or chains are blocked by the casing of the gas turbine itself. Equally, the use of a hoist can however already be restricted by the lines, pipes or cables to the point that there is very little space available for movement.
In order for example to avoid such drawbacks, the applicant has already proposed, in one of their patent applications, installing a linear rail system on the gas turbine which can support a burner as the component, in order to be able to install or remove the latter in a targeted manner. This linear rail system, described in WO 2013/030230 A2 has two tracks and is itself secured to another, second rail system on which it can be moved to the respective burner opening. In this context, the second rail system is designed as an endless circular track or a circular arc which is attached, in the region of the burner mating flange, to the casing of the gas turbine such that the first, linear rail system can be moved to each burner opening in a targeted manner.
Although the linear rail system known from the prior art permits flexible working, bringing the linear rail system into precise alignment with the burner opening proves to be disadvantageous and sometimes protracted. Owing to the ability of the prior art linear rail system to move on a circular track or on a circular arc, it is sometimes not readily possible for a component, which has been removed, to be aligned with the casing of the gas turbine to the point that the component flange and the component mating flange can be connected to one another without further adjustment. However, post-adjustment can prove time-consuming.
Post-adjustment of this kind can be avoided in part if, for example, the rail system is screwed directly to the burner mating flange by means of an annular attachment flange, as taught for example in EP 2236939 A1. However, this still requires adjustment, specifically when the attachment flange is applied against the burner mating flange and at the same time the entire weight of the rail system has to be supported. Only once the flange and the mating flange are connected sufficiently securely is the adjustment finished.
The adjustment can be simplified by means of holes or bolts which are provided in the annular attachment flange of the rail system and can easily be aligned with suitable mating fitting regions on the burner mating flange. Adjustment aids of this type are disclosed for example in US 2005/0076490 A1.
However, adjustment aids of this type have the drawback that the operator cannot perform an easily detectable visual adjustment during application. The annular form of the attachment flange means that it can be applied against the burner mating flange in innumerable ways. In this context, the annular shape itself permits no orienting during the alignment procedure, rather the adjustment can be properly undertaken only when the flange and mating flange are already very close to one another or are in contact with one another. Even then, it may be necessary to re-orient, which is not always easy to carry out due to the considerable weight of the rail system.